The proposal describes research that evaluates the hypothesis that cardiac vagal tone and vagal reactivity measures will contribute to the identification of neonates at greatest risk for developmental problems. Cardiac vagal tone is assessed as a functional indicator of central nervous system regulation of autonomic function. The proposal outlines four experiments designed to demonstrate that cardiac vagal tone will augment clinical risk factors and existing assessment procedures in predicting developmental outcome. The proposal describes procedures to measure individual response profiles in the vagal tone parameters of level, development, and reactivity. Experiments 1, 2, and 3 will evaluate long term outcome of neonates who have been previously evaluated in either the neonatal intensive care unit (NICU) or fullterm nursery. Experiments 4 and 5 represent at integrated research project that builds on previous finding of the level, development, and reactivity of cardiac vagal tone in preterm neonates in the NICU. Experiments 4 and 5 will focus on the dimensions of vagal reactivity and will assess the integrative capacity of the central control of vagal function by evaluating the coordination among cardiac vagal tone, heart rate, and sucking in response to gustatory stimulation (5% and 15% sources). In addition, individual differences in vagal evaluate whether knowledge of the integrative capacity of the vagal system derived from responses to gustatory stimuli is related to developmental outcome in high-risk and low-risk preterm neonates (Experiment 4) and fullterm neonates with and without perinatal asphyxia (Experiment 5). Follow-up studies are designed to evaluate at 9-months vagal reactivity during sustained attention, vagal reactivity to novelty, cognitive development, motor development, and temperament. At 3 years of age, developmental outcome is assessed via measures of cognitive processes, social behavior, and temperament. The objective of Experiments 4 and 5 is to evaluate whether the gustatory stimulation paradigm can be used in the NICU as a diagnostic procedure that will provide additional information regarding health status and developmental outcome. The proposed research is an attempt to demonstrate that non-invasive health status and is related to developmental outcome.